[R] if statement and for loop question

Kai Yang y@ngk@|9999 @end|ng |rom y@hoo@com
Mon May 31 18:26:51 CEST 2021


  Hi Jim,
Sorry to post "same" question, because 
1. I was asking to use plain text format. I have to post my question again. But I don't know if it is working.
2. I'm a beginner for R (< 2 month). It may not easy for me to ask a "clear" R question. My current work is to transfer my SAS code into R, especially for data manipulation part. 
I'll do my best to ask a non."same" question later.
Thanks,
Kai
    On Sunday, May 30, 2021, 10:44:41 PM PDT, Jim Lemon <drjimlemon using gmail.com> wrote:  
 
 Hi Kai,
You seem to be asking the same question again and again. This does not
give us the warm feeling that you know what you want.

testdf<-data.frame(a=c("Negative","Positive","Neutral","Random","VUS"),
 b=c("No","Yes","No","Maybe","Yes"),
 c=c("Off","On","Off","Off","On"),
 d=c("Bad","Good","Bad","Bad","Good"),
 stringsAsFactors=FALSE)
testdf
match_strings<-c("Positive","VUS")
testdf$b<-ifelse(testdf$a %in% match_strings,testdf$b,"")
testdf$c<-ifelse(testdf$a %in% match_strings,testdf$c,"")
testdf$d<-ifelse(testdf$a %in% match_strings,testdf$d,"")
testdf

I have assumed that you mean "zero length strings" rather than
"zeros". Also note that your initial code was producing logical values
that were never assigned to anything.

Jim

On Mon, May 31, 2021 at 2:29 AM Kai Yang via R-help
<r-help using r-project.org> wrote:
>
> Hello List,I have a data frame which having the character columns:
>
> | a1 | b1 | c1 | d1 |
> | a2 | b2 | c2 | d2 |
> | a3 | b3 | c3 | d3 |
> | a4 | b4 | c4 | d4 |
> | a5 | b5 | c5 | d5 |
>
>
>
> I need to do: if a1 not = "Positive" and not = "VUS" then values of  b1, c1 and d1 will be zero out. And do the same thing for the a2 to a5 series.
> I write the code below to do this. But it doesn't work. Would you please correct my code?
> Thank you,
> Kai
>
>
> for (i in 1:5)
> {
>  if (isTRUE(try$a[i] != "Positive" && try$a[i] != "VUS"))
>  {
>    try$b[i]== ''
>    try$c[i] == ''
>    try$d[i]== ''
>  }
> }
>
>
>        [[alternative HTML version deleted]]
>
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